Aqueous polymer composition and method of preparing thereof

Abstract

An aqueous polymer composition comprises (A) a specific emulsion polymer comprising structural units of a cycloalkyl (meth)acrylate, structural units of an acetoacetoxy or acetoacetamide functional monomer, and structural units of a phosphorous acid monomer, a salt thereof, or mixtures thereof; and (B) a specific amount of a waterborne resin comprising at least one fatty acid ester segment and having a number average molecular weight of 20,000 g/mol or less, based on the total dry weight of the emulsion polymer and the waterborne resin. A coating composition comprising such aqueous polymer composition provides coatings made therefrom with improved anti-corrosion property.

What is claimed is: 
     
         1 . An aqueous polymer composition comprising,
 (A) an emulsion polymer comprising, based on the weight of the emulsion polymer,   from 5% to 28% by weight of structural units of a cycloalkyl (meth) acrylate,   from 0.1% to 10% by weight of structural units of an acetoacetoxy or acetoacetamide functional monomer,   from 0.05% to 10% by weight of structural units of a phosphorous acid monomer, a salt thereof, or mixtures thereof,   from zero to 10% by weight of an additional ethylenically unsaturated acid monomer, and   structural units of an additional ethylenically unsaturated nonionic monomer; and   (B) from 0.7% to 7.8% by dry weight of a waterborne resin comprising at least one fatty acid ester segment and having a number average molecular weight of 20,000 grams per mole or less, based on the total dry weight of the emulsion polymer and the waterborne resin.   
     
     
         2 . The aqueous polymer composition of  claim 1 , wherein the waterborne resin is selected from the group consisting of a waterborne epoxy ester, an unsaturated fatty acid ester modified acrylic copolymer, or mixtures thereof. 
     
     
         3 . The aqueous polymer composition of  claim 2 , wherein the unsaturated fatty acid ester modified acrylic copolymer comprises, by weight based on the weight of the unsaturated fatty acid ester modified acrylic copolymer, 20% or more of structural units of (meth)acrylic acid. 
     
     
         4 . The aqueous polymer composition of  claim 2 , wherein the unsaturated fatty acid ester modified acrylic copolymer is a castor oil or sulphated castor oil modified acrylic copolymer. 
     
     
         5 . The aqueous polymer composition of  claim 2 , wherein the waterborne epoxy ester comprises a reaction product of an unsaturated fatty acid and optionally an additional carboxylic acid-group-containing compound with an epoxy compound. 
     
     
         6 . The aqueous polymer composition of  claim 5 , wherein the waterborne epoxy ester is a (meth)acrylic acid functionalized waterborne epoxy ester. 
     
     
         7 . The aqueous polymer composition of  claim 1 , wherein the acetoacetoxy or acetoacetamide functional monomer is selected from the group consisting of acetoacetoxyethyl methacrylate, acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, allyl acetoacetate, acetoacetoxybutyl methacrylate, 2,3-di(acetoacetoxy)propyl methacrylate, or mixtures thereof. 
     
     
         8 . The aqueous polymer composition of aby-one of  claim 1 , wherein the cycloalkyl (meth)acrylate is selected from the group consisting of cyclohexyl methacrylate, cyclohexyl acrylate, methcyclohexyl acrylate, or mixtures thereof. 
     
     
         9 . The aqueous polymer composition of  claim 1 , wherein the phosphorous acid monomer is selected from the group consisting of phosphoethyl methacrylate, phosphoethyl acrylate, allyl ether phosphate, or mixtures thereof. 
     
     
         10 . The aqueous polymer composition of  claim 1 , wherein the emulsion polymer comprises, by weight based on the weight of the emulsion polymer, from 10% to 25% of structural units of the cycloalkyl (meth)acrylate; from 1.5% to 4% of structural units of the acetoacetoxy or acetoacetamide functional monomer; from 1.5% to 4% of structural units of the phosphorous-containing acid monomer, the salt thereof, or mixtures thereof; and structural units of the additional ethylenically unsaturated nonionic monomer; and optionally, from zero to 3% of structural units of an ethylenically unsaturated functional monomer having one or more functional groups selected from ureido, amide, amino, silane, hydroxyl, or combinations thereof. 
     
     
         11 . The aqueous polymer composition of  claim 1 , comprising from 1% to 7.5% by dry weight of the waterborne resin, based on the total dry weight of the emulsion polymer and the waterborne resin. 
     
     
         12 . The aqueous polymer composition of  claim 1 , wherein the emulsion polymer further comprises structural units of a polymerizable surfactant. 
     
     
         13 . A method of preparing the aqueous polymer composition of  claims 1  by admixing the emulsion polymer with the waterborne resin. 
     
     
         14 . A coating composition comprising the aqueous polymer composition of  claims 1  and optionally a pigment.